U.S. patent number 6,787,682 [Application Number 10/007,445] was granted by the patent office on 2004-09-07 for absorbent foam wound dressing.
This patent grant is currently assigned to Hollister Incorporated. Invention is credited to Thomas H. Gilman.
United States Patent |
6,787,682 |
Gilman |
September 7, 2004 |
**Please see images for:
( Certificate of Correction ) ** |
Absorbent foam wound dressing
Abstract
A highly conformable and absorbent polymeric foam wound dressing
is disclosed, such dressing being particularly useful in preventing
pooling of fluid in a draining wound while at the same time
maintaining surrounding skin surfaces in a relatively dry
state.
Inventors: |
Gilman; Thomas H. (Spring
Grove, IL) |
Assignee: |
Hollister Incorporated
(Libertyville, IL)
|
Family
ID: |
21726196 |
Appl.
No.: |
10/007,445 |
Filed: |
November 5, 2001 |
Current U.S.
Class: |
602/58; 602/42;
602/43; 602/46; 602/54 |
Current CPC
Class: |
A61F
13/023 (20130101); A61F 2013/0074 (20130101) |
Current International
Class: |
A61F
13/02 (20060101); A61F 13/00 (20060101); A61F
013/00 () |
Field of
Search: |
;602/41-59 ;128/888,889
;604/304-308 ;424/443-449 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO 94/21207 |
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Sep 1994 |
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WO |
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WO 97/11658 |
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Apr 1997 |
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WO |
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WO 02/05737 |
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Jan 2002 |
|
WO |
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WO 04/05737 |
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Jan 2002 |
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WO |
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Primary Examiner: Lewis; Kim M.
Attorney, Agent or Firm: Marshall, Gerstein & Borun
LLP
Claims
What is claimed is:
1. A wound dressing comprising a foam layer of soft, hydrophilic
polymeric foam having bodyside and backside surfaces; a base layer
of elastomeric film adhered to said bodyside surface of said foam
layer; said base layer having at least one generally centrally
located opening therein exposing said foam layer through said
opening; said base layer having a bodyside surface coated with a
hypoallergenic pressure-sensitive adhesive for adhesively
contacting wound and surrounding skin surfaces at a wound site; and
a vapor-permeable liquid-impermeable elastomeric backing layer
extending over said backside surface of said foam layer; said
backing layer being unattached to said backside surface of said
foam layer over said centrally located opening of said base
layer.
2. The wound dressing of claim 1 in which said backing layer
includes a peripheral edge portion secured to said base layer about
said foam layer.
3. The wound dressing of claim 1 or 2 in which said foam layer is
composed of a soft hydrophilic polyurethane foam.
4. The wound dressing of claim 1 or 2 in which said elastomeric
film of said base layer is gas-permeable and
liquid-impermeable.
5. The wound dressing of claim 1 or 2 in which a flexible and
stretchable foraminous layer extends over the surface of said
backing layer opposite from said foam layer.
6. The wound dressing of claim 5 in which said flexible foraminous
layer is formed of soft, stretchable polymeric foam.
7. The wound dressing of claim 5 in which said foraminous layer has
a multiplicity of openings of regular shape for viewing said
backing layer therethrough.
8. The wound dressing of claim 7 in which said openings in said
flexible foraminous layer are generally rectangular in shape and
are arranged in a grid pattern.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
U.S. Pat. No. 5,086,764 discloses various forms of wound dressings
in which an absorbent fabric 12 is located either in a wound cavity
beneath a base sheet 14 or directly above an aperture 18 in that
base sheet. In either case, the absorbent fabric 12 is removable or
separable from the base sheet 14 so that it may be easily changed
without disturbing that sheet when the fabric becomes saturated. In
some versions, a back sheet 38 extends over the absorbent fabric
and is secured thereto by a pressure-sensitive coating 40.
Soft, compressible, highly absorbent and hydrophilic foams are also
known for medical and dental use as disclosed, for example, in U.S.
Pat. No. 3,903,232. While such foams may be of different polymeric
compositions, the polyurethane foams disclosed in the
aforementioned patent are exceptionally soft and hydrophilic,
expanding quickly as they absorb aqueous fluids.
Other U.S. patents illustrating the state of the art are U.S. Pat.
Nos. 5,146,362, 5,603,946, 5,244,457, 4,907,570, and 5,056,510.
A main aspect of the present invention lies in providing an
improved wound dressing for preventing pooling of liquid in a
draining or exuding wound while at the same time protecting the
wound against contamination and maintaining the surrounding skin
surfaces in a relatively dry state. The dressing utilizes a soft,
hydrophilic polymeric foam layer that readily expands into a wound
cavity as it absorbs wound exudate.
In the dressing of this invention, the absorbent foam layer is
permanently secured to the backside of an elastomeric base film.
The base film is vapor-permeable but liquid impermeable except for
one or more generally central openings through which a portion of
the underside of the foam layer is exposed. A pressure-sensitive
adhesive coats the underside or bodyside surface of the film for
securing the dressing to body surfaces at a wound site. The
adhesive coating (or each such coating) of the base film is
discontinuous or micro-porous so that it does not block the
transmission of moisture vapor through the film.
An elastomeric backing layer extends over the back surface of the
foam layer but ideally is not directly attached or adhered to the
foam layer. The lack of adherence or attachment is important
because it enhances conformability of the dressing to anatomical
contours, and to changes in such contours as a patient moves about,
and allows limited displacement of the foam layer away from the
backing layer and expansion into a wound cavity when the dressing
is in use. If desired, the outermost surface of the elastomeric
backing layer may be covered by a soft foraminous foam layer having
a multiplicity of wide openings, preferably taking the form of a
stretchable foam grid, to assist in the handling, delivery, and
application of the dressing at a wound site.
Other features, advantages and objects of the invention will become
apparent from the specification and drawings.
DRAWINGS
FIG. 1 is an exploded perspective view of a wound dressing
embodying this invention.
FIG. 2 is a schematic cross-sectional view of the dressing.
FIG. 3 is an enlarged fragmentary sectional view showing the
dressing at a wound site.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Polymeric foams that are soft, exceptionally hydrophilic, and
readily expandable as they absorb aqueous fluids are known in the
art, one such foam being a polyurethane foam disclosed in
aforementioned patent U.S. Pat. No. 3,903,232. Such a foam is
prepared with polyoxyethylene, polyisocyanates, water and certain
surfactants and has an exceptionally fine, uniform, soft,
hydrophilic cell structure. The foam is of low density and may be
characterized as being of open cell or semi-open cell in structure.
It has an extreme affinity for aqueous fluids, being able to absorb
and retain many times its weight of such fluids and
characteristically swelling or expanding as it does so. When used
in a wound dressing, such an expandable hydrophilic foam has been
found capable of absorbing a substantial volume of fluid from a
draining or exuding wound to prevent the pooling of liquid while at
the same time maintaining the wound bed in moist and protected
condition.
While a polyurethane foam of the type so described is preferred, it
is believed that other soft, highly-absorbent polymeric foam
materials are known and may be used in the dressing of this
invention. An example of one polyurethane foam found to be
particularly effective is available from Rynel Ltd., Inc.,
Boothbay, Me. under the designation Foam HPFL00562.
Referring to the drawings, the numeral 10 generally designates a
wound dressing having a soft, absorbent, compressible, hydrophilic
foam layer 11, a base film 12, and a backing layer or film 13. Both
the base film and backing film are elastomeric and
vapor-transmissible as well as liquid-impermeable. More
specifically, such elastomeric films should have moisture vapor
transmission values approximating or exceeding those of healthy
skin. In general, the MTVR for each film should be at least 250 cc
per square meter per 24 hours. A polyurethane film having a
thickness within the general range of 0.25 mil to 2.0 mil,
preferably about 0.5 mil, has been found suitable for both the base
film and backing film, but other elastomeric film materials having
similar properties may be used. For example, a polyester block
copolymer marketed under the trademark "Hytrel" by du Pont De
Nemours, Wilmington, Del. is believed suitable for both the base
film and backing film.
Base film 12 has its bodyside surface coated with a suitable
hypoallergenic pressure-sensitive adhesive 14. A conventional
medical-grade acrylic adhesive is suitable but other
pressure-sensitive adhesives such as hydrocolloid and hydrogel
adhesives might be used. Adhesive layer 14 should be vapor
permeable by reason of diffusibility or because of discontinuity or
microporosity, all as well known in the art. To protect the
adhesive layer 14 prior to use of the dressing, such layer is
covered by a removable release sheet 15 shown only in phantom in
FIG. 2. Such release sheet may be formed of siliconized paper or
any other suitable material.
The back surface of base film 12 is permanently secured to the
bodyside surface of foam layer 11, preferably by means of a
vapor-permeable adhesive layer 16 which may be of the same
composition as pressure-sensitive adhesive layer 14. It will be
observed that foam layer 11 is smaller in outline than base film 12
and backing film 13 (which are of equal size) so that the borders
of the respective films extend outwardly beyond the periphery of
foam layer 11. In FIG. 1, broken lines 12a and 13a schematically
delineate the border portions of the base and backing films that
extend outwardly beyond the foam layer 11 and are secured to each
other in such border area, preferably by means of the same adhesive
layer 16 that secures foam 11 to base film 12. In a preferred
embodiment of the invention, the upper or back surface of foam
layer 11 is not adhered or otherwise secured directly to the
bodyside surface of the backing layer 13. A spacing between the two
is shown in FIG. 2 but such spacing is shown only for illustrative
purposes and may not exist, at least until such time as the
dressing is applied to a wound.
In the embodiment illustrated in the drawings, dressing 10 is shown
to be generally rectangular in outline, but it is to be understood
that such shape is not critical. It is important that the area of
the dressing be substantially larger than that of the wound over
which the dressing is applied so that the pressure-sensitive
adhesive coating 14 sealingly engages the skin surfaces surrounding
the wound over which the dressing extends. Instead of being
rectangular in shape, the dressing may be generally circular or
oval in outline or alternatively may be of any of a variety of
selected shapes having areas substantially larger than the wound W
to be covered.
Base film 12 with its pressure-sensitive adhesive coating 14 has at
least one centrally-located opening 17 of a size smaller than that
of the wound W over which the dressing extends. When the dressing
is applied over a draining wound, the soft, deformable and highly
absorbent foam layer 11 expands downwardly through opening 17 as it
absorbs fluid from the wound cavity (as indicated by arrows 18 in
FIG. 3). The elastomeric base film 12 is secured by
pressure-sensitive adhesive layer 14 to the skin surfaces
surrounding the wound W and, as shown in FIG. 3, that portion of
the base film 12 surrounding opening 17 also extends downwardly
into the wound about the edges 23 of the wound cavity. The base
film thereby maintains the skin surface about the wound cavity in
relatively dry condition and, in addition, directs liquid into that
portion of the foam layer 11 disposed directly above base film 12
beyond the border of opening 17.
In a preferred embodiment in which the backing film 13 is free of
attachment to the top surface of foam layer 11, the foam layer is
free to expand downwardly into the wound cavity and away from
elastomeric layer 13 as depicted in FIG. 3. The backing film thus
presents no resistance to downward expansion of the foam. Moisture
vapor may pass through backing film 13 as indicated by arrows 19,
so that liquid absorbed by the foam layer 11 may convert to vapor
form and pass through vapor-permeable backing layer 13.
In a preferred embodiment, dressing 10 is provided with an optional
delivery-assisting layer 20 which takes the form of a soft,
foraminous layer of stretchable polymeric foam extending over
backing film 13. A multiplicity of wide apertures 21 are provided
in layer 20 with such apertures preferably being of rectangular
shape and giving layer 20 a grid-like appearance. The grid-portion
of layer 20 may be secured by any suitable pressure-sensitive
adhesive to the upper surface of elastomeric film 13.
As shown in FIGS. 1 and 2, layer 20 may be provided with opposite
end portions 22 that project outwardly to function as tabs that be
easily gripped by a user for purposes of holding and applying the
dressing to a wound site. While a foam material as disclosed in
U.S. Pat. No. 5,902,260 (the disclosure of which is incorporated by
reference herein) is believed particularly suitable for layer 20,
other materials, such as stretchable nonwoven polymeric materials,
may instead be used. Further, layer 20, if used at all, may be
weakly attached to backing film 13 by an adhesive that allows layer
20 to be peeled away from the backing film 13 after the dressing
has been applied. In that connection, the outwardly-projecting tab
portions 22 of the foam layer are also useful in gripping that
layer and separating it from backing film 13.
While in the foregoing I have disclosed an embodiment of the
invention in considerable detail for purposes of illustration, it
will be understood by those skilled in the art that many of these
details may be varied without departing from the spirit and scope
of the invention.
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